Prosecutors called Scott Peterson "the worst kind of monster" in the closing arguments delivered during the final day of the penalty phase of the double-murder trial Thursday, the Associated Press reports.

As the final witness in the double-murder trial's penalty phase, a frail-looking Jackie Peterson took the stand in the packed Redwood City, Calif., courtroom Wednesday morning and pleaded for her son's life.

It was an emotional day in court Tuesday as the penalty phase began and Scott Peterson simply watched as his former mother-in-law screamed at him from the witness stand for killing his pregnant wife, Laci.

After deliberating for only six hours, a jury found Scott Peterson guilty of first-degree murder in the death of his wife Laci, it was announced in the Redwood City, Calif., courtroom Friday afternoon.